Which is better between Solar energy and Wind mill?

That depends on where you are. If you are in Mecca, solar energy. That is where you get the maximum insolation on Earth. Wind power (mills, turbines, etc.) are best in the Great Plains and in the ocean, also good in the mountains, if sited correctly.

Solar energy is a bit more reliable because it generates electricity in almost every weather and even generates little electricity on cloudy days. So people only have to plan for cloudy rainy weather, which they can forecast with apps like AccuWeather or Climacell. On the other hand, wind energy requires a lot many considerations.

I'd say neither.

Both are no guarantee since the sun isn't always shining without clouds and the wind is not always blowing.

I would look for providers of electricity that is made from waste, biogases or other renewables sources.

The negative aspects of both solar and wind as an energy source outweighs the benefits of it. Yes, it's renewable, but installing solar energy is really costly, if you are building a solar park you will have to clear the land and once everything's set you have to manage it to keep it from soiling or recievers getting dirty or snowy. Solar panels are not really compatible with even the smallest shadow (the smallest shadows makes for a big production loss) and they last about 25 years on full capacity. That will give you about 5 years of worth with gaining and going plus economically on it. It takes about 20 years for it to balance out economically.